The invention relates to a security element for securing value documents, comprising a first polymer containing a feature substance, which is at least partially surrounded by a second polymer, wherein the first polymer is a hydrophobic, water-insoluble polymer which, at an elevated pH value and at an elevated ambient temperature at a treatment duration of at least 30 minutes, can be converted into a hydrophilic, water-soluble polymer, and the second polymer is a hydrophilic, water-soluble polymer. The invention further relates to methods for producing the security element and to a value document having the security element.
Paper recycling processes to which, for ecological reasons, ideally also value documents, in particular banknotes, which are worn or which have production defects, are to be subjected, usually take place at elevated temperature and at an elevated pH value. Conventional security elements for securing value documents, for example mottling fibers or planchets with feature properties such as, for example, UV luminescence, IR absorption or photochromism, however, are so stable that they are not destroyed under the conditions of the paper recycling processes. Typically, the conventional security elements are only damaged and thus remain in the paper stock as visible, disturbing fragments. Consequently, worn value documents, but also security paper containing security elements as starting material for producing banknotes that does not meet the specification for further processing, for example as a result of production errors (e.g. incorrect paper thickness, tears in the paper web, incorrect concentration of security elements), cannot readily be subjected to a conventional paper recycling process for security reasons. The paper producer thus incurs high costs for disposal.
It is the object of the invention to make available an improved security feature for securing value documents. It is desirable in particular to make available a security element that has a sufficient stability to water and moisture, so that the security element is not destroyed under the conditions of the paper production, but that is at the same time so unstable that the security element is destroyed under the more drastic conditions of the paper recycling process. The invention further relates to making available production methods for such a security element and to making available a value document equipped with the security element.
These objects are achieved by the combinations of features defined in the independent claims. Preferred embodiments are the subject matter of the subclaims.